Commentary: Arginine vasotocin preprohormone is expressed in surprising regions of the teleost forebrain

Recently, Rodriguez-Santiago et al. (1) reported that arginine vasotocin (AVT) preprohormone mRNA is expressed in pallial and subpallial nuclei of the cichlid fish, Astatotilapia burtoni. Specifically, they claim expression in putative homologs of the mammalian extended amygdala, hippocampus, striatum, and septum. The authors present these results as "surprising" because, to date, this expression has never been reported even when the same methods [i.e., in situ hybridization (ISH)] were applied to A. burtoni (2) and other fish species [see Table 1 in Ref. (1) in addition to zebrafish (3) and catfish (4)]. We argue that making claims that contradict longstanding conclusions in the field of teleost vasotocin-associated neuroanatomy and neurochemistry warrants better evidence. We identify technical issues regarding in situ specificity, qPCR design, and reporting. Importantly, we also point out statements where the authors miscite previous research regarding brain region homologies of proposed vasotocin and vasopressin (AVP) cell populations.